1. Field of the Invention
The present invention relates to an information recording method, an information recording apparatus, a program for information recording, and a storage medium for recording information on rewritable multilayer information recording media such as dual-layer DVD+RWs (Digital Versatile Disc+ Rewritable).
2. Description of the Related Art
Recordable DVDs include DVD+Rs, which are write-once DVDs, and DVD+RWs, which are rewritable DVDs. These disks are recordable DVDs having high playback compatibility with single sided single layer read-only DVDs. Vigorous research and development efforts are being made for increasing the speed and capacity of these recordable disks.
One of them is a single sided dual layer read-only DVD (hereinafter simply referred to as “dual-layer DVD”). There are two types of recording methods for the dual-layer DVD: Parallel Track Path (PTP) where the track of the second layer runs from the inside to the periphery as that of the first layer and Opposite Track Path (OTP) where the track of the second layer runs from the periphery to the inside. According to PTP, the radial positions of the starting addresses of the data areas of the first layer and the second layer are equal, and both start at a physical address 30000H. Further, a Lead-out area is disposed after the data areas. According to OTP, the radial position of the starting address of the data area of the second layer is equal to the radial position of the end address of the data area of the first layer, and the physical address of the starting position of the data area of the second layer is the bit-flipped address of the end address of the data area of the first layer. If there is a difference in size between the data areas of the first layer and the second layer, the difference area becomes a Lead-out area. For instance, if the end address D1 of the data area of the first layer and the end address D2 of the data area of the second layer satisfy D1>D2 in a PTP disk, the difference area D1-D2 becomes a Lead-out area. Thus, data is also recorded in an area of the second layer corresponding to an area in which data is recorded in the other recording layer. This is to avoid, for instance, the occurrence of a problem in that if no data is recorded at the same radial position in the second layer when a read laser happens to be focused on the second layer in a seek to a target address at the time of a user reproducing the data of the first layer, the data of the first layer cannot be reproduced as a result of the problem of the inability to obtain address information.
Meanwhile, vigorous research and development efforts are also being made for increasing the speed and capacity of recordable information recording media, of which one is a single sided dual layer DVD+R (hereinafter simply referred to as “dual-layer DVD+R”) having playback compatibility with the dual-layer DVD. The dual-layer DVD+R has a recording capacity of 8.4 Gbytes, which is approximately twice that of the conventional single-layer DVD+R having a data capacity of 4.7 Gbytes. Recorded data can be read out with DVD players or DVD-ROM drives capable of playing back the dual-layer DVD.
In the dual-layer DVD+R, logical addresses are assigned successively from the starting address of the data area of the first layer, and the logical addresses are successive from the end address of the data area of the first layer to the starting address of the data area of the second layer. That is, when a user records data successively, the recording is started from the starting address of the data area of the first layer, and when the recording is completed up to the end address of the data area of the first layer, the recording goes on to be performed from the starting address of the data area of the second layer. Thus, in dual-layer DVD+R recording, a user can perform recording with the recording layers being transparent thereto. Accordingly, a user may end data recording in the middle of the data area of the second layer or without recording any data in the second layer. For instance, if a user completes data recording in the middle of the data area of the second layer, that is, with an unrecorded area being present in the data area of the second layer, this results in a disk layout incompatible with the read-only dual-layer DVD with the unrecorded area remaining in the data area of the second layer. For instance, if a read laser happens to be focused on the second layer in a seek to a target address when a user reproduces the data of the first layer, there occurs a problem in that the data of the first layer cannot be reproduced as a result of the problem of inability to obtain address information if no data is recorded at the same radial position in the second layer. The same problem results if a user ends data recording without recording any data in the second layer.
In this regard, with respect to the dual-layer DVD+R, it has been proposed (unpublished) to ensure reading in read-only drives by establishing logical compatibility with the dual-layer DVD by recording, for instance, dummy data having a user data attribute or Lead-out in the unrecorded area of the second layer. However, according to this proposal, the compatibility with the dual-layer DVD can be established if recording is completed, but the compatibility with the dual-layer DVD cannot be established in a state halfway through recording.
Further, for instance, with respect to the dual-layer DVD+R, it has been proposed (unpublished) to perform recording by dividing a data area into multiple sessions. In the case of performing recording in one session in the data area of the first layer in an apparatus according to this proposal, it is possible to ensure the conventional single-layer DVD+R playback compatibility in read-only drives by recording data session by session, while it is impossible to ensure the dual-layer DVD+R playback compatibility in read-only drives. This is because no data is recorded in the data area of the second layer at the same radial position as the recorded area of the first layer.
These problems result from the fact that the dual-layer DVD+R is an unrewritable write-once disk. That is, if dummy data or the like is recorded in the unrecorded data of the second layer while recording is not completed, data overwriting occurs in subsequent recording, so that there occurs a problem in that the recorded data cannot be read out.